According to the prior art, preparation of dialkyl and trialkylsilanes from silane is not easy to achieve. Prior art methods require strenuous conditions and/or afford low yields. For example, lower dialkylsilanes can be prepared from the monosubstituted compounds and the olefins by reacting them at 250.degree.-450.degree. C.; U.S. Pat. No. 2,786,862, Mar. 26, 1957. The monoalkylsilanes are first prepared from silane and olefins of 2-5 carbon atoms by heating at 25.degree.-250.degree. C. under pressure; U.S. Pat. No. 2,537,763, Jan. 9, 1951.
The methods of these patents appear to have been an advance in the art, for it was reported in the same time frame that "No method for the direct alkylation or alkoxylation of monosilane, SiH.sub.4, has previously appeared in the literature"; Peake, et al, J. Am. Chem. Soc. 74, 1526 (1952). Furthermore, although Peake et al showed that phenyl sodium and lithium alkyls will react with silane, they were unable to alkylate silane using Grignard reagents, or phenylcalcium iodide, diphenyl calcium, or diethyl zinc. This work indicates there are material distinctions between various classes of organometallic reagents.
White et al, J. Am. Chem. Soc. 76, 3897 (1954) reacted ethylene and silane at 450.degree.-510.degree. C. by continuously circulating the gaseous reactants through the reaction zone. A mixture of products was formed including monoethyl-, diethyl-, and triethylsilane, as well as disilane, Si.sub.2 H.sub.6, trisilane, Si.sub.3 H.sub.8, and ethyldisilane C.sub.2 H.sub.5 Si.sub.2 H.sub.5. With hindsight, one could expect such a complex product mixture since silane begins to decompose at 380.degree. C.